One-part solvent-based adhesive for bonding polymer materials

ABSTRACT

What is disclosed are adhesives and bonding methods employing a single coat of a solvent-based adhesive that effectively bonds thermoplastic polymers and especially thermoplastic elastomers. The adhesive components are a organosilane component selected from organosilane-isocyanate adduct and isocyanato-organosilane, a post-chlorinated polymer containing propylene repeating units or derivative thereof, and solvent. Also disclosed are methods for joining a rigid, structural substrate to a molten polymer such as a TPE via injection molding or extrusion. Durable adhesion between the adhesive treated portion of the rigid sub-strate and the melt-processed polymer is achieved with or without a previous heat treatment on the adhesive-coated substrate prior to joining to the thermoplastic melt.

FIELD OF THE INVENTION

The invention pertains to solvent-based polymer-bonding adhesives, suchas thermoplastic elastomers and elastomer vulcanizates to similar ordissimilar substrates. The adhesives employ a silane-containingcomponent and a chlorinated polymer.

BACKGROUND OF THE INVENTION

It is well known that thermoplastic articles formed from a variety ofpolyolefin-containing plastic materials have widely varying surfaceproperties, including surface tension, roughness and flexibility. Assubstrates used in forming a bonded composite, achieving durability,i.e., environmentally-resistant bonding has been a continuing challenge.There are many known adhesion promoters used as tie-coats, or primersfor paints on polyolefin-based materials. Applying a tie coat isnormally an added step in the coating process. The adhesion promoter isusually applied in a thin layer, normally about 6 to 10 microns (μm).

Known adhesion promoters for coatings olefin-based thermoplasticsurfaces contain chlorinated polyolefins, some examples of which aredescribed in U.S. Pat. Nos. 4,997,882; 5,319,032 and 5,397,602. Othersinclude carboxy-modified polyolefins. See U.S. Pat. No. 4,299,754teaching carboxylate-modified polyolefins in aromatic or aliphatichydrocarbon or a chlorinated hydrocarbon.

Performance obtained with chlorinated polyolefin in tie-layers forcoatings is not predictive for bonding of olefin-based articles tosubstrates typically encountered, such as steel and aluminum. This isdemonstrated in an article in the Journal of Coating Technology, 65, No.827 p. 21 (1993) for chlorinated polyolefins.

In the case of bonding rigid substrates in-line to a molten olefin-basedthermoplastic profile or in insert-injection molding, temperatures abovethe processing temperature or heat dwell times must be avoided.Melt-processible thermoplastic elastomers, or TPE's, TPV's, TPO's(hereinafter collectively, “TPE”) are desirable materials for formingsuch products as window channels, weatherstrips, and various automobiletrim pieces. A rigid, structural substrate such as metal or rigidthermoplastic is joined in-line to the molten profile. In similarfashion, there are known methods where a rigidifying substrate and TPEare joined by insert injection molding. Improved adhesion between thesubstrate and TPE is desired.

U.S. Pat. No. 5,051,474 to Warren, et al discloses adhesives comprisinga linear polyester polyurethane, a halogenated polyolefin, a phenolicresin, and a cross-linker. The formulation is preferably utilized as atwo-component adhesive for bonding polymer blend-based thermoplasticelastomers to various substrates such as metal.

U.S. Pat. No 5,268,404 to Mowrey discloses a one-part adhesivecomposition exhibiting strong rubber-to-metal bonds with excellentenvironmental resistance without the necessity of first priming themetal surface. The composition comprises a halogenated polyolefin, anaromatic nitroso compound, metal oxide such as zinc oxide or magnesiumoxide, and optionally a vulcanizing agent such as sulfur or selenium, aphenolic epoxy resin, or carbon black.

U.S. Pat. No. 5,432,246 to Fenn et al. discloses a silane oligomer madefrom a secondary amino-alkoxy silane, a polyisocyanate and optionally asingle isocyanate group, resulting in a substituted urea, with no freeremaining isocyanate groups.

U.S. Pat. No. 6,512,039 to Mowrey discloses an adhesive designed to bondmetal to peroxide cured elastomers. A representative formulationcomprises from 10 to 20% of chlorosulfonated polyethylene, from 15-25%of an acid scavenger, from 35-45% of a polymaleimide, from 5-15% ofprecipitated silica, and 10-20% of an isocyanatosilane.

EP 0187171 discloses primers for thermoplastic polyolefins.Representative of these primer is a composition comprising chlorinatedpolyolefin, such as polypropylene, or graft-modified polypropylene, acrosslinkable binder and a crosslinking agent selected from amines,amidoamines, isocyanates, poly-isocyanates, cyanurates, and acrylatescontaining —OH or —COOH groups.

Representative adhesives containing polyisocyanates, or bonding agentssuch as aminosilanes are known. U.S. Pat. No. 4,031,120 (Lord) disclosesone-coat adhesives based on isocyanatosilane or anisocyanate-organosilane adduct. A variety of film formers are suggested.Optimally, the adhesive includes a nitroso compound. It would beindustrially important to provide good primary adhesion bonding of aone-coat adhesive to more than one type of TPE under conditions oflimited heat, such as extrusion bonding or cladding, or insert injectionmolding.

SUMMARY OF THE INVENTION

In one aspect the invention provides a method for bonding a TPE to asubstrate by employing a single coat, liquid, solvent-based adhesivewhich comprises an organosilane component selected fromorganosilane-isocyanate adduct (A) or isocyanato-organosilane (B), and apost-chlorinated polymer comprising propylene repeating units. Thetypical nonvolatile component amounts are 10 to 90 wt. % of theorganosilane component and 90 to 10 wt. % of post-chlorinated polymerand an overall solids content range of 5 to 50 wt. % in organic solvent.

In a method aspect, the invention includes a method of bonding a rigid,structural substrate to a molten polymer comprising contacting a moltenpolymer extrudate with a treated substrate. The substrate is treated byapplying adhesive to the substrate, and drying. Another method aspect isa method for bonding a polymer injection melt which comprises contactingthe injection melt to a treated substrate contained in the injectionmold. The substrate is treated by applying adhesive and drying. Aftercontacting the injection melt to the adhesive-treated portion of thesubstrate, the composite is cooled, and removed from the mold. Durableadhesion between the adhesive treated portion of the inserted rigidsubstrate and the melt-processed polymer is achieved with or without aheat treatment applied to the adhesive-coated substrate prior to joiningto the TPE.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polymeric film former employs a base polymer which ispost-chlorinated polypropylene (CPP). The base polymer comprisespropylene repeating units. The film former can encompass derivatives ofpost-chlorinated polypropylene. The base polymer weight averagemolecular weight is from 5,000 to 60,000, and preferably from 15,000 to45,000. The chlorine content should be in the range of 10 to 60 weight%, and preferably chlorine content is from 20-50 weight %. As the basepolymer comprising propylene repeating units, these include crystallinepolypropylene, noncrystalline polypropylene, ethylene-propylenecopolymer, ethylene-propylene-diene copolymer, propylene-C₄-C₁₀-α-olefin copolymer may be used. The base polymer may actually bea blend of polypropylene homopolymer and a copolymer comprisingpropylene repeating units may also be used. As an example of a blend, 25to 95 wt. % of a propylene homopolymer is combined with from 5 to 75 wt%, preferably 10 to 60 wt. % of a random propylene copolymer containingrepeating units based on 1-butene, 1-pentene, 1-hexene, 1-heptene, or1-octene. Most preferred is chlorinated polypropylene availablecommercially under the Hardlen® designation. Examples include Hardlen13-LP chlorinated polypropylene from Toyo Kasei Kogyo Co., Ltd., andproducts under the Eastman CP-343-1 and CP-343-3 designations.

Many suitable derivatives of chlorinated polypropylene useful herein areknown. Such a representative derivative is a polymer comprisingpropylene repeating units which is modified by incorporating one or moreethylenic unsaturated monomers, e.g., acrylate or methacrylate monomers,macromonomers, vinyl-functional organosilanes, liquid terminal ethylenicpolydiene polymers and/or other graft-functional materials such asmaleic acid anhydride, or maleimides. These are typically introducedinto solution with chlorinated polypropylene, as taught in JapaneseKokai No. 24316 (1976), No. 36128 (1982), No. 215667 (1986), US4,608,415 and US 5,130,373. The starting CPP material is for exampleHardlen® 14-LLB manufactured by Toyo Kasei Kogyo Co., Ltd. of weightaverage molecular weight about 30,000, a chlorine content 27%, as a 30%solution in toluene. Up to 40 wt. parts total of monomers, and/ormacromonomers and/or liquid polymers, etc., are present with 100 wt.parts of CPP in a peroxide-initiated reaction in solution of organicsolvent. In another chlorinated polypropylene derivative, chlorinatedpolypropylene is derivatized (“maleated”) with 0.1 to 10 wt. “phr”(parts per hundred CPP) of maleic acid anhydride according to knownmethods. As a further alternative derivative, maleic acid anhydride andacryl- or methacryl-modified hydrogenated polybutadiene, areincorporated using peroxide under known conditions.

As preferred derivatives of chlorinated polypropylene there are includedmaleic anhydride modified, or maleated chlorinated polypropylene. Anexemplary maleic anhydride derivative can be prepared by combining 100wt. parts of chlorinated polypropylene having a chlorine content, forexample of 30% with 10 wt. parts of maleic anhydride and 300 parts ofchlorobenzene in a reactor equipped with a reflux condenser, anddissolving by heating at 110° C. To this solution, 10 wt. parts ofbenzoyl peroxide are added thereto over a 6-hour period of addition.After completion of the addition, the mixture is allowed to furtherreact under agitation for 3 hours at the same temperature. After thereaction is completed, chlorobenzene and unreacted maleic anhydride aredistilled off under atmospheric pressure followed by vacuum stripping at1 mm Hg at 140° C. The bound maleic anhydride content of chlorinatedpolypropylene is about 8 wt. %, and the bonded chlorine content is about27%. This derivative is readily taken up in the solvent used forformulating the adhesive having a typical solids range of 5 to 25 wt. %.Commercially available derivatives of chlorinated polypropylene modifiedwith maleic anhydride include CP 343-1, from Eastman Chemical Company,Kingsport Tenn., HARDLEN® CY-9122P, from Toyo Kasei Kogyo, Ltd., Osaka,Japan, and HYPALON® CP-826, available from DuPont Dow Elastomers L.L.C.,Wilmington, Del.

Specific exemplary derivatizing agents for CPP include liquid typepolybutadiene number average molecular weight 500 to 5000, acrylic acidoligomer having a hydroxyl value of 95, molecular weight 570, astyrene/acrylonitile macromonomer having a terminal methacryloylradical, isobutyl methacrylate macromonomer having a terminalmethacryloyl radical, with molecular weight 6000, and2-ethylhexylcarylate. The acrylic, maleic- or methacrylic-modifiedpolybutadienes useful for derivatizing are known and made according toknown methods such as by esterification reaction of hydrogenatedOH-terminal polybutadiene to acrylic acid or methacrylic acid, (ii) byan addition reaction of the diisocyanate-hydroxyacrylate orhydroxymethacrylate prepolymer to OH-polybutadiene, (iii) by aring-opening esterification reaction of hydrogenated polybutadienecontaining a carboxyl group to glycidyl acrylate or glycidylmethacrylate, (iv) by an addition reaction of iminolacrylate oriminolmethacrylate to hydrogenated polybutadiene containing a carboxylgroup, or (v) by the Ene reaction. Likewise, other suitable chlorinatedpolypropylene derivatives can be prepared using known polyolefinmodifying agents containing functional groups such as sulfonate groups,carboxylic acid anhydride groups, hydroxyl groups, epoxide groups,carboxylic acid ester groups, carboxylic acid amide groups, carboxylicacid groups, and the like can be reacted with chlorinated polypropylene.

The adhesive compositions of this invention are prepared by conventionalmixing in one or more organic solvents. For ease of application, as isconventional in this art, the components are mixed and dispersed ininert organic liquid diluents which are the primary carrier of thehomogeneous, refined mixture of solids, and once the wet adhesivecomposition has been applied, the carrier is readily removed byevaporation. Examples of suitable organic solvents are, aromatic andhalogenated aromatic hydrocarbons such as benzene, toluene, xylene,chlorobenzene, dichlorobenzene, and the like; halogenated aliphatichydrocarbons such as trichloroethylene, perchloroethylene, propylenedichloride and the like; ketones such as methyl ethyl ketone, methylisobutyl ketone, and the like; ethers, naphthas, etc., includingmixtures of such carriers. Preferred organic solvents are xylene andtoluene, ortho- and para-chlorotoluene, optionally in combination withtetrachloroethylene. The amount of solvent employed is that whichprovides a composition suitable for use as an easily applied adhesiveand ordinarily such as to provide a total solids content (TSC) rangingfrom about 5 to 50 wt. %, preferably about 10 to about 30 wt. %, andmore preferredly 10 to 20 wt. %.

Isocyanatosilane adducts are prepared by effecting a reaction between aco-reactive organosilane and a polyisocyanate by adding theorganosilane, preferably as a dilute solution, to the polyisocyanate,also preferably diluted, at a temperature in the range from about 10° toabout 100° C., while agitating the mixture by a mechanical stirrer orsimilar device. A stoichiometric amount of equivalents of isocyanategroups in the polyisocyanate can be reacted with co-reactive groups ofthe organosilane, or preferably, a stoichiometric excess of isocyanategroups to co-reactive organosilane is used. While not essential, asuitable catalyst, e.g., dibutyltin dilaurate, can be employed. Thereaction readily proceeds when catalyst is employed, and is mildlyexothermic

In one embodiment the organosilane-containing component is an adduct (A)of an isocyanate-reactive organosilane and a molar excess ofpolyisocyanate that is co-reactive therewith (“organosilane-isocyanateadduct”). The organosilane is coupled through a functional hydrocarbylgroup bonded directly to the silicon. This linkage can be represented inabbreviated fashion as —NH—C(O)—A-R—Si, wherein representative groups Ainclude O, S, >N—, and R is a divalent hydrocarbyl C₁-C₂₀ group,especially C₂-C₄. Isocyanate-organosilane adducts are taught in U.S.Pat. No. 4,031,120, and prepared by reacting a multifunctionalorganosilane and a polyisocyanate, in dilute solution, conducted at atemperature in the range from about 10° C. to about 100° C. whileagitating the mixture by a mechanical stirrer or similar device. Anoptional conventional catalyst, such as dibutyltin dilaurate, can beemployed. The reaction is instantaneous and exothermic when catalystsare employed. It is most preferred that the amount of polyisocyanatepresent during the reaction be such as to ensure obtaining an resultingadduct having at least one free isocyanate group.

A specific illustration of an isocyanate-organosilane adduct isdisclosed in U.S. Pat. No. 5,623,044 and is the reaction product of asecondary aminoalkoxy silane and a polyisocyanate. As an example, 485 gof HDl (Desmodur N-100 ex. Mobay) (2.59 equivalents) and 225 g of alkylphthalate are charged to a resin kettle equipped with a mechanicalagitator, a thermometer, a N₂ inlet adapter and an addition funnel. Themixture is thoroughly mixed and purged under N₂ blanket. About 300 g ofsilane (N,N-bis[(3-trimethoxysilyl)-propyl]amine) (0.88 equivalents) isslowly added to the mixture. The resulting adduct has an isocyanatecontent of 7.0%.

Representative isocyanate-reactive organofunctional silanes suitable formaking an adduct with a polyisocyanate include without limitation theknown silanes that contain an abstractible hydrogen, such as amino,mercapto, and hydroxy groups, ——COOH, ——NH——, ——CONH₂, ——CONH——including polyols, polyamines, polymercaptans and polyacids. Examples ofstarting silanes are N,N-bis[(3 -triethoxysilyl)propyl]amine;N,N-bis[(3-tripropoxysilyl)propyl]amine;N-(3-trimethoxysilyl)propyl-3-[N-(3-trimethoxysilyl)-propylamino]propionamide;N-(3-triethoxysilyl)propyl-3-[N-3-triethoxysilyl)-propylamino]propionamide;N-(3-trimethoxysilyl)propyl-3-[N-3-triethoxysilyl)-propylamino]propionamide;3-trimethoxysilylpropyl 3-[N-(3-trimethoxysilyl)-propylamino]-2-methylpropionate; 3-triethoxysilylpropyl3-[N-(3-triethoxysilyl)propylamino]-2-methyl propionate;3-trimethoxysilylpropyl 3-[N-(3-triethoxysilyl) -propylamino]-2-methylpropionate; and the like. A commercial example silane isgamma-mercaptopropyl-trimethoxysilane (available as A189 from UnionCarbide) or N,N′-bis((3-trimethoxysilyl)propyl) amine.

Aminofunctional organosilanes are most preferred and include but are notlimited to aminofunctonal organosilanes having the structure (A)

wherein R, R¹, R², and “a” are as previously defined for structure (A);and R⁵ is selected from the group consisting of hydrogen, monovalentaliphatic radicals having from 1 to 8 carbon atoms, monovalentcycloaliphatic radicals having from 4 to 7 ring carbon atoms, phenyl,alkaryl radicals having 6 nuclear carbon atoms and containing one ormore substituent alkyl groups having from 1 to 4 carbon atoms, and—R⁶—NH—R⁷, wherein R⁶ is selected from the group consisting of divalentaliphatic, cycloaliphatic and aromatic radicals having from 1 to 20carbons, there being preferably at least two carbon atoms separating anypair of nitrogen atoms, with R⁶ being preferably an alkylene group of 2to 9 carbon atoms; and R⁷ being the same as R⁵ and preferably ishydrogen. Specific representative isocyanate-reactive organosilanes,where “g” and “d” represent gamma and delta, respectively, arehydroxypropyltrimethoxysilane, hydroxypropyltriethoxysilane,hydroxybutyltrimethoxysilane, g-aminopropyltrimethoxysilaneg-aminopropyltriethoxysilane, methylaminopropyltrimethoxysilane,g-aminopropyltripropoxysilane, g-aminoisobutyltriethoxysilane,g-aminopropylmethyldiethoxysilane, g-aminopropylethyldiethoxysilane,g-aminopropylphenyldiethoxysilane, d-aminobutyltriethoxysilane,d-aminobutylmethyldiethoxysilane, d-aminobutylethyldiethoxysilane,g-aminoisobutylmethyldiethoxysilane,N-methyl-g-aminopropyltriethoxysilane,N-phenyl-g-aminoisobutylmethyldieth oxysilane,N-ethyl-d-aminobutyltriethoxysilane,N-g-aminopropyl-g-aminopropyltriethoxysilane,N-.beta.-aminoethyl-g-aminoisobutyltriethoxysilane,N-g-aminopropyl-d-aminobutyltriethoxysilane,N-aminohexyl-g-aminoisobutylmethyidiethoxysilane,methylaminopropyltriethoxysilane, g-aminopropylmethoxydiethoxysilane,and the like. Examples of commercially available amino-functionalorganosilanes include Silquest™ Y-9669,N-phenyl-gamma-aminopropyltrimethoxysilane, Silquest™ A1170,bis-(g-trimethoxysilylpropyl)amine, Silquest™ A1100,g-aminopropyltriethoxysilane, Silquest™ A1110,g-aminopropyltrimethoxysilane, and Silquest™ A1120,N-(β-aminoethyl)-gamma-aminopropyltrimethoxysilane, available from OSI,Inc.

Representative hydroxyl group-containing organosilanes include but arenot limited to compounds of the general structure B:

wherein R is a divalent aliphatic, cycloaliphatic or aromatic saturatedor unsaturated radical having from 1 to 20 carbon atoms, and ispreferably an alkylene radical having from 1 to 9, most preferably 2 to4, carbon atoms; R¹ is a monovalent aliphatic, cycloaliphatic oraromatic radical having from 1 to 20 carbon atoms, and is preferablyselected from the group consisting of alkyl radicals having from 1 to 4carbon atoms, cycloalkyl radicals having from 4 to 7 ring carbon atoms,and aryl radicals having 6, 10, or 14 nuclear carbon atoms, andincluding such aryl radicals containing one or more substituent alkylgroups having from 1 to 4 carbon atoms; R² is a monovalent aliphatic,cycloaliphatic or aromatic organic radical containing from 1 to 8 carbonatoms, and is preferably selected from the group consisting of alkylradicals having from 1 to 4 carbon atoms, R³—O—R⁴, and

where R³ is an alkylene group having from 1 to 4 carbon atoms (methyl,ethyl, propyl, butyl) and R⁴ is an alkyl group having from 1 to 4 carbonatoms; and a is zero or 1, preferably zero;

Representative mercaptofunctional silanes reactive with polyisocyanatesinclude but are not limited to those having the structure (C)

wherein R, R¹, R² and “a” are as previously defined for structures A orB; Commercially available mercaptosilane is sold by OSI as SILQUESTA-189, mercaptopropyltrimethoxysilane.

The preferred starting material organosilane comprises a single organicchain having from 1 to 20 carbon atoms bonded to silicon, said chainhaving at least one extractable hydrogen atom, said extractable hydrogenatom preferably being attached to a functional group separated from thesilicon atom by at least 3 interconnected carbon atoms. The activehydrogen moiety is in any position in the molecule whereby this groupdisplays significant activity according to the Zerewitnoff testdescribed by Wohler in the Journal of the American Chemical Society,Vol. 49, p. 3181 (1927).

Starting polyisocyanates for making isocyanate-organosilane adducts (A)can be aliphatic aliphatic, cycloaliphatic, arylaliphatic, heterocyclicor aromatic polyisocyanate, or mixtures thereof, with an averageisocyanate functionality of at least about 2.0 and an equivalent weightof at least about 80. Preferably, the isocyanate functionality of thepolyisocyanate is at least about 2.0, more preferably at least about2.2, and is more preferably at least about 2.3; and is preferably nogreater than about 4.0, more preferably no greater than about 3.5, andis most preferably no greater than about 3.0. Examples of usefuldiisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate (TDI), diphenylmethane 4,4′-diisocyanate (MDI),1,4-phenylene diisocyanate, dicyclohexylmethane diisocyanate (H₁₂-MDI),isophorone diisocyanate (IPDI), 1,6-hexanediisocyanate, and1,3-(α,α,α′,α′-tetramethyl)xylylene diisocyanate (TMXDI)2,2,4-trimethylhexamethylene-1,6-diisocyanate;hexamethylene-1,6-diisocyanate, diphenylmethane-4,4′-diisocyanate,triphenylmethane-4, 4′4-triisocyanate,3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, polymethylenepolyphenylisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate,2,6-tolylene diisocyanate, 1,5-naphthalenediisocyanate,naphthalene-1,4-diisocyanate, diphenylene-4,4′-diisocyanate,3,3′-bi-tolylene-4,4′-diisocyanate, ethylene diisocyanate,propylene-1,2-diisocyanate, butylene-2,3-diisocyanate,ethylidenediisocyanate, butylidenediisocyanate,xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate,methylcyclohexyldiisocyanate, cyclopentylene-1,3-diisocyanate,cyclohexylene-1,4-diisocyanate,4,4′-methylene-bis(cyclohexylisocyanate),p-phenylene-2,2′-bis(ethylisocyanate), 4,4′-diphenyleneether-2,2′-bis(ethylisocyanate), tris(2,2′,2″-ethylisocyanate benzene),5-chloro-phenylene-1,3-bis(propyl-3-isocyanate),5-methoxy-phenylene-1,3-bis(propyl-3-isocyanate),5-cyanophenylene-1,3-bis(propyl-3-isocyanate),4-methyl-phenylene-1,3-bis(propyl-3-isocyanate), and the like.Polyisocyanates can be formed as dimers, trimers, tetramers and the likeusing customary and known, suitable catalysts. In an oligomer, freeisocyanate groups may be present along with uretdione, biuret,isocyanurate, urea and/or allophanate groups. Oligomerization can becarried out readily with low molecular mass polyols such astrimethylolpropane or homotrimethylolpropane, glycerol, and the like.Dimers are known for instance from U.S. Pat. No. 2,671,082.

Preferred diisocyanate functional compounds include IPDI, MDI, andblends, such as a mixture of isomers, e.g., 2,4-tolylene diisocyanateand 2,6-tolylene diisocyanate. After formation of an adduct ofpolyisocyanate and organosilane, free isocyanate groups preferablyremain, but in alternative embodiments, free NCO may optionally bepartially or completely blocked using conventional blocking agents, oradjacent groups internally blocked by formation of uretdione structures,for example. Examples of known blocking agents are derived from anysuitable aliphatic, cycloaliphatic, aromatic, or alkylaromaticmonoalcohol, monoamide, monoamine, or monooxime. Ketoximes arewell-known and unblock at relatively low temperatures such as 120° C.More sterically hindered, acid-stable blocking groups include lactams ofaminoacids, such as the lactam of 6-aminohexanoic acid and/orbenzotriazole. Other blocking groups include the active methylenecompounds such as ethyl sec-butyl malonate, acetoacetates, e.g., C₁-C₈alkyl acetoacetates, for example, n-butyl acetoacetate, isobutylacetoacetate, sec-butyl acetoacetate, and t-butyl acetoacetate; andbetadiketones such as acetylacetone.

In an alternative to an isocyanatosilane adduct (A) as silane componentin the adhesive is an isocyanotosilane such as are made by pyrolysis ofcarbamate (silylorganohalide and metal cyanate) or reacting siliconhydride and allyl isocyanate. Isocyanatosilanes containing at least one,or more than one hydrolyzable group and one free isocyanate group areknown in the art and typically represented by the structure

wherein R¹ is a monovalent aliphatic, cycloaliphatic or aromatic radicalhaving from 1 to 20 carbon atoms, and is preferably selected from thegroup consisting of alkyl radicals having from 1 to 4 carbon atoms,cycloalkyl radicals having from 4 to 7 ring carbon atoms, aryl radicalshaving 6, 10, or 14 nuclear carbon atoms, and such aryl radicalscontaining one or more substituent alkyl groups having from 1 to 4carbon atoms; R² is a monovalent aliphatic, cycloaliphatic or aromaticorganic radical containing from 1 to 8 carbon atoms and is preferablyselected from the group consisting of alkyl radicals having from 1 to 4carbon atoms, —R³—O—R⁴, and

where R³ is an alkylene group having from 1 to 4 carbon atoms and R⁴ isan alkyl group having from 1 to 4 carbon atoms; a is zero or 1, andpreferably is zero; and Z is a divalent organic radical attached to thesilicon atom via a carbon-silicon bond. The exact nature of the Zradical is not critical, i.e., the radical can have any configurationand combination of groupings that are compatible with the isocyanatogroups. For example, the Z radical can be a hydrocarbon radical, or itcan contain linkages such as ether, ureido, urethane, and thiourethanelinkages. The Z radical can contain substitutent groups such as halogen.The isocyanatosilane preferably contains an average of at least onehydrolyzable silane group, and preferably two such groups in addition toat least one free isocyanate group per molecule. Useful ranges ofmolecular weight are from 200 to about 2,000. An example of anisocyanatosilane useful in the present invention is Silquest™ A-1310,which is gamma-isocyanatopropyltriethoxysilane.

The adhesive can optionally further contain known and customaryadjuvants including acid scavengers such as zinc oxide, magnesium oxide;lead salts such as dibasic lead phosphite, dibasic lead phthalate,monohydrous tribasic lead maleate, tetrabasic lead fumarate, andmixtures thereof; epoxy compounds or resins, such as glycidyl ethers ofbisphenol A, epoxysilanes, and epoxyphenolics; fillers such asprecipitated silica, TiO₂; reinforcing agents such as carbon black; andtinting or coloring agents such as color pigments and dyes.

The adhesive according to the invention is versatile and bonds a varietyof elastomers and low-polarity polymeric substrates to structural parts,such as metallic window channels, trim strips, bumper guards, edgemoldings and the like. The polymeric materials as well as the substratesare not limited as to the variety of compositions and shapes. Shapedarticles include foils, extrusion profiles, coils, injection moldedparts that are bondable. Bonding of the polymer material can be to asimilar or different material. A rigid thermoplastic can be bonded to anelastomeric material. An elastomer can be bonded to a dissimilarsubstrate such as wood, metal, or glass. Representative metals areselected from any of the common structural metals such as iron, steel(including stainless steel), lead, aluminum, copper, brass, bronze,MONEL®, nickel, zinc, and treated metals with phosphatizing,galvanizing, and the like. Prior to bonding, a metal surface istypically cleaned according to one or more methods known in the art suchas degreasing, grit-blasting and zinc-phosphatizing. The non-metallicsubstrates include glass panels, woven or nonwoven glass fabrics,continuous rovings of glass, such as E-glass; fabrics, fibers or rovingsof polyamides, polyester, and aramids, e.g., Kevlar, a trademark of E.I. du Pont de Nemours Co., (Inc.),

Aluminum and steel profiles are especially bondable to TPE with theadhesive, in the absence of a nitroso compound. The bondable polymericsubstrate materials include the low surface energy (<45 dynes/cm)polyolefins (e.g. polypropylene, polyethylene,polyethylene-co-propylene, copolymers of C₄-C₈ α-olefins with ethyleneand/or propylene, polyethylene foams, polypropylene foams,ethylene-propylene-diene terpolymer (EPDM) rubbers, ethylene-propylenerubbers (EPR), etc.), styrene-ethylene-butene-styrene copolymer (SEBS),styrene-ethylene-propylene-styrene copolymer (SEPS),styrene-isoprene-styrene (SIS) rubbers, styrene-butadiene-styrene (SBS)rubbers, to name a few of these.

The adhesive compositions are applied to the substrate surface in aconventional manner such as by dipping, spraying, brushing, and thelike. The substrate surface is dried before contacting to the polymer tobe bonded. In one bonding method, the surface has been treated with theadhesive and the polymer pressed together with the adhesive layer inbetween, and the assembly is heated to the desired temperature toleratedby the polymer. The conditions are preselected upon considering theparticular polymer or elastomer being bonded and whether or not it iscured after contact or cured prior to contact with the substrate. If thepolymer is a curable type and is uncured, the curing is to be effectedduring bonding, the conditions will be dictated by the polymercomposition. Vulcanizable elastomers will generally be cured at atemperature of from about 140° C. to about 200° C. for a time rangingfrom about 5 to about 60 minutes. If the polymer of the curable type hasbeen cured, the bonding temperature may range from about 90° C. to above180° C. for from 15 to about 120 minutes. Alternatively, in situationswhere applicable, the adhesives can be interspersed between the surfacesto be joined as a solid film or tape (100% solids adhesive system) withbonding being accomplished as before.

Extrusion Bonding

A preferred method aspect according to the invention includes thebonding of thermoplastic processed polymer to a continuous or elongatedstructural member which has been pre-treated with the adhesive. Thetreated member is passed adjacent to or through an extruder die, andjoined to the molten polymer extrudate, followed by cooling of thejoined article. The treated substrate may be preheated off-line, and maybe brought to a desired temperature state at the time of joining withthe extrudate. This can be effected by feeding an elongated structuralprofile, such as a metal strip, a shaped profile such as a channel intoan extruder die adapted to receive the elongated member. Durableadhesion between the adhesive treated portion of the profile substrateand the extruded polymer is achieved with or without a previous heattreatment on the adhesive pre-treated substrate prior to joining in thisknown manner.

In another method aspect, a structural article is inserted by the pieceinto the cavity of an injection mold, melt processible polymer isinjected into the closed mold cavity thereby contacting the pretreatedsurface of the inserted article, causing a bonding between the polymerand substrate. The adhesive is especially adapted for bondingthermoplastic injected polymer within the mold cavity in this knownmanner. This method comprises treating a predetermined side, or sectionof a side of a rigid substrate, e.g., stamped or shaped metal with theadhesive herein, and drying. The treated substrate is inserted into thecavity of the injection mold at a predetermined location, and the moldis closed. Molten thermoplastic is injected into the mold contacting theadhesive treated portion of the substrate. After cooling sufficient forejecting the bonded article, the finished molding is ejected or removedfrom the parted mold. Durable adhesion between the adhesive treatedportion of the inserted rigid substrate and the melt process polymer isachieved with or without a previous heat treatment on theadhesive-coated substrate prior to joining to the thermoplastic melt.

EXAMPLE 1

Adhesive examples A-I, were prepared by mixing. % DRY WEIGHTS RAWMATERIALS A B C D E F G H I Chlorinated polypropylene (A) 95.0 87.0 80.089.0 80.0 67.0 80.0 67.0 57.0 MDI - Polydiphenylmethane- 11.0 20.0 33.0diisocyanate (B) Adduct of (B) with γ- 20.0 33.0 43.0 aminopropyltriethoxysilane (80:20 by wt.) amino alkyl trimethoxysilane (C) 5.0 13.020.0 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

Adhesives above were prepared in xylene at solids ranges between 21-35%.

The above adhesives were applied to aluminum coil panels at a DFT offrom 0.0003 to 0.0004 inch (0.007-0.010 mm). Adhesive was applied to thealuminum panels using a #40 draw down bar. Polymer materials injectionmolded to the adhesive treated panels which were inserted into the moldcavity were Santoprene® and Sarlink® TPE. Santoprene® is supplied byAdvanced Elastomer Systems. Sarlink® supplied by DSM Elastomers. Afterthe adhesive was applied to the metal panels, solvent was driven off byheating allowing a peak metal temperature of 435° F. (223° C.) in anoven set at 485° F. (251° C.).

Samples where indicated were preheated prior to injection moldingbonding for 2′@250° F. (121° C.). In either instance, with or without apreheat, excellent bonds were obtained in accordance with the invention.Insert molding bonding was obtained using a Toyo® injection moldingpress under the following conditions:

Injection Pressure 1,100 psi (7,000 kPa), mold temperature: 160° F. (71°C.) Cooling cycle: 45 sec.; zone temperatures: 1-450° F. (232° C.),2-450° F. (232° C.), 3-440° F. (226° C.), 4-430° F. (221° C.), and5-420° F. (215° C.)

Adhesion testing was completed using pliers to peel the polymer from themetal substrate by hand. In the T-peel testing the aluminum panels bentoften the adhesive was released from the metal. The percent rubberrepresents the amount of rubber adhering to the metal substrate afterpeeling as a percent of the bond area. Santoprene ® Sarlink ® 0′ 2′ 0′2′ On aluminum PREHEAT PREHEAT PREHEAT PREHEAT ADHESIVE A 8% 8% 30% 45%ADHESIVE B 0% 0%  0%  0% ADHESIVE C 0% 0%  0%  0% ADHESIVE D 10%  5% 98%60% ADHESIVE E 5% 2% 38%  0% ADHESIVE F 0% 0% 70%  0% ADHESIVE G 50% 85%  85% 73% ADHESIVE H 50%  55%  73% 85% ADHESIVE I 45%  80%  43% 97%

The combination of chlorinated polypropylene and silane-isocyanateadduct bonds a both types of TPE as indicated by the minimum 50% polymerretention by the hand-peel test, as compared to adhesives A-F containingeither component alone. Improvement in bonding with and without apreheating step. Most of the failure mode was the result of the metalbeing bent during testing.

The above examples G, H and I were repeated using stainless steel as thesubstrate. Stainless steel Santoprene ® Sarlink ® 0′ 2′ 0′ 2′ PREHEATPREHEAT PREHEAT PREHEAT ADHESIVE G 83% 98% 93% 75% ADHESIVE H 73% 97%63% 93% ADHESIVE I 55% 55% 88% 89%

EXAMPLE 2

The following adhesives were applied at 0.0003-0.0004 inch (0.007-0.010mm) to aluminum coil panels to compare different film forming polymers.The peak metal temperature after drying the adhesive was 435° F. (224°C.) in an oven set at 500° F. (260° C.). Each TPE was dried overnite at160° F. (71° C.) before molding. Adhesive in Xylene Raw Materials % TSC45A 45B 45C 45D 45E Chlorinated polypropylene 15 70 0 0 0 0Chlorosulfonated PE-1* 10 0 70 0 0 0 Chlorosulfonated PE-2* 20 0 0 70 00 Chlorinated NR* 30 0 0 0 70 0 Modified polyolefin 25 0 0 0 0 70(Eastman 440-1) Silane adduct (Ex. 1) 19.75 30 30 30 30 30 % Total 16.0016.00 16.00 16.00 16.00 solids Dry Wt % 100 100 100 100 100Mixing: Add adhesive and roll for 1 hour.*as taught in U.S. Pat. No. 4,031,120 absent nitroso cpd.

Insert molding bonded composites were obtained using a Toyo® injectionmolding press under the following conditions:

Injection Pressure 1,100 psi (7,000 kP), mold temperature: 160° F. (71°C.) Cooling cycle: 45 sec.; zone temperatures: 1-450° F. (232° C.),2-450° F. (232° C.), 3-440° F. (226° C.), 4-430° F. (221° C.), and5-420° F. (215° C.)

Failure modes are: R-polymer; RC-polymer-to-adhesive;CM-adhesive-to-metal Testing: Primary Adhesion Adhesive R TR RC CM CP toElastomer: Santoprene ® - 2″/min peel rate 45A 99 1 95 5 97 — 3 — — 45B100 100 — — 100 — — 45C 100 100 — — 100 — — 45D 100 100 — — 100 — — 45E100 100 — — 100 — — to Elastomer: Sarlink ® - 2″/min peel rate 45A 90 10100 95 — 10 — — 45B 100 100 — — 100 — — 45C 100 100 — — 100 — — 45D 100100 100 45E 100 100 — — 100 — —

The peel results illustrate that Example 2-A bonds metal well to bothTPE polymers whereas example 2B-2F fails in adhesive to polymer mode.

EXAMPLE 3

The adhesive formulations of Example 2 were tested in bonding otherpolymers such as elastomers under compression molding duringvulcanization without a prebake. The adhesives were spray applied onpre-heated (150° F./65° C.) zinc phosphatized steel panels. Dry filmthickness was 0.001 inch (0.025 mm). The treated panels were eachinserted in a compression mold and raw elastomer stock applied. TheElastomers were cured as follows:

Natural rubber 1-13′@340° F. (171° C.)

Natural rubber 2-13.5′@340° F. (171° C.)

Nitrile rubber 1-19.5′@340° F. (171° C.)

SBR 1-18′@340° F. (171° C.)

Peroxide cured EPDM-7.5′@340° F. (171° C.)

Peroxide cured silicone-5′@350° F. (176° C.)

“*” denotes sweep, a loss of bonding due to movement of adhesive by theinjection melt flow in the mold.

Failure modes are: R-rubber; RC-rubber-to-cement; CM-cement-to-metal.HP—denotes hand peeled. Where indicated, primary adhesion peel strengthvalues in N/m were obtained per ASTM D429B. Percent of failure mode isof the bond area. % % % Ex. N/m R RC CM Nat. Rubber 1 45A HP 20 80 HP 4060 — — 30 70 45B HP 20 80 HP 40 60 — — 30 70 45C HP 90 10 HP 10 90 — —50 50 45D HP 100 HP 100 — — 100 — 45E HP 50 50 HP 30 70 — — 40 60 Nat.Rubber 2 45A HP 100 875 75 25 875 — 75 63 45B HP 100 HP 90 10 — — 95 1045C HP 100 HP 10 90 — — 10 95 45D HP 100 HP 100 — — 100 — 45E HP 50 50HP 100 — — 50 75 Nitrile Rubber 1 45A 7700 5 95 1068 30 70 9280 18 — 8345B 11031 5 10 85 11381 10 10 80 11206 8 10 83 45C HP 100 HP 100 — — —100 45D 16460 100 18210 100 17334 100 — — 45E HP 100 HP 100 — — 100 100SBR 1 45A 13132 10 70 20 7879 80 20 10506 10 75 20 45B 9105 5 20 75 857920 80 8930 5 20 78 45C HP 5 95 6303 10 90 6303 — 8 93 45D HP 100 HP 100— — 100 — 45E HP 100 HP 50 50 — — 75 50 EPDM 45A 6828 95 5 8755 85 10 57879 90 8 5 45B 6128 30 70 5077 10 90 5603 20 — 80 45C 2626 5 95 2276 595 2451 — 5 95 45D 4902 95 5 5253 60 40 5077 78 23 — 45E* 3151 5 95 36775 65 30 3502 5 65 63 Silicone 45A 100 100 — — 100 — 45B 100 100 — — 100— 45C 100 100 — — 100 — 45D 100 100 — — 100 — 45E* 80 20 70 30 — — 75 25

1. A liquid adhesive comprising an organosilane-containing componentselected from the group consisting of a organosilane-isocyanate adductand an isocyanato-organosilane, a polymer comprising post-chlorinatedpropylene repeating units, and an organic solvent.
 2. The adhesiveaccording to claim 1 wherein said polymer has a weight average molecularweight of from 5,000 to 60,000 and a chlorine content of from 10 wt. %to 60 wt. %.
 3. The adhesive according to claim 1 wherein said polymeris selected from crystalline polypropylene, noncrystallinepolypropylene, ethylene-propylene copolymer, ethylene-propylene-dienecopolymer, and propylene-C₄-C₁₀-α-olefin copolymer.
 4. The adhesiveaccording to claim 1 wherein said post-chlorinated polymer is maleated.5. The adhesive according to claim 1 wherein said organic solvent isselected from the group consisting of aromatic and halogenated aromatichydrocarbons.
 6. The adhesive according to claim 1 having a total solidscontent of from 5 to 50 wt. %.
 7. The adhesive according to claim 1wherein said organosilane-containing component is aorganosilane-isocyanate adduct containing the linkage —NH—C(O)-A-R—Si,wherein A is O, S, or N, and R is a divalent C₁-C₂₀ hydrocarbyl group.8. The adhesive according to claim 1 wherein the organosilane-containingcomponent is an isocyanatosilane containing at least one hydrolyzablegroup and at one free isocyanate group and having the structure (E)

wherein R¹ is a monovalent aliphatic, cycloaliphatic or aromatic radicalhaving from 1 to 20 carbon atoms; R² is a monovalent aliphatic,cycloaliphatic or aromatic organic radical containing from 1 to 8 carbonatoms, —R³—O—R⁴, and

where R³ is an alkylene group having from 1 to 4 carbon atoms and R⁴ isan alkyl group having from 1 to 4 carbon atoms; a is zero or 1, and Z isa divalent organic radical attached to the silicon atom via acarbon-silicon bond.
 9. A method for joining a polymer extrudate to acontinuous or elongated structural member which has been treated withthe adhesive of claim 1 comprising passing the adhesive-treatedsubstrate adjacent to or through an extruder die, and joining the memberto the extrudate to form a joined article, and cooling the joinedarticle.
 10. The method of claim 9 wherein said joined article is awindow channel.
 11. A method for joining an injection molded polymer toa structural member which has been treated with the adhesive of claim 1,comprising inserting the adhesive-treated member into an injection moldcavity adapted to receive the member, exposing an adhesive-treatedsurface of the member to the mold cavity, injecting said polymer intothe cavity contacting the polymer with the treated surface of themember, and cooling the polymer.